MASM MUL Operation Accepts Only One Operand (74882)

The information in this article applies to:

Microsoft Macro Assembler (MASM) 5.1
Microsoft Macro Assembler (MASM) 6.0

This article was previously published under Q74882

SUMMARY

The assembly language multiplication instruction MUL accepts only one operand. The second operand is implied to be either the AX or the AL register depending on whether an 8-bit multiplication or 16-bit multiplication is being performed.

If a second operand is specified, the Microsoft Macro Assembler (MASM) version 6.0 will generate the following error:

error A2008: syntax error : ,

MASM versions 5.1 and 5.1a generate the following warning:

warning A4001: Extra characters on line

MORE INFORMATION

The sample code below can be used to illustrate this situation. Assembling the code with MASM version 5.1, 5.1a, or 6.0 will result in one of the above errors.

Sample Code

; Assemble options needed: none

    .MODEL small
    .CODE
    mul ah, 10
    END

Modification Type:	Minor	Last Reviewed:	10/29/2003
Keywords:	KB74882